With all the years, and all the gears, (Hey! That rhymes) there will ba a BIT of slop in there. ALL of my trucks, have a bit of slop in the driveline. If you're hearing noises, something isnt right. Older vehicle, will make a bit more noise. Straight cut gears, as compared to the "slanted" cut gears. But a "noise"? There is probably a problem in there. But even with all of the good people here, and their expertise.... Pause for affect. This is kinda' like doing, mail order brain surgery. you might need to take it to a driveline shop, and get their opinion. I hope that the diff, is full of oil, and that the spider gears aren't shot. As my truck is a B-2G, I'm not familiar with the smaller trucks. Can you pull the diff cover, and take a look inside?